Cycas chevalieri

Cycas chevalieri is a cycad of north-central Vietnam, known from the provinces of Nghệ An, Hà Tĩnh, Quảng Bình and Quảng Trị; its presence in neighbouring Laos has not been confirmed. Described in 1931 by the French botanist Jacques Leandri in the Flore générale de l’Indo-Chine, from incomplete material collected for Auguste Chevalier, whose name it bears, this species of the genus Cycas was long confused with Cycas balansae, of which it was treated as a synonym. It is now accepted as a species, and the IUCN lists it as Vulnerable (2023).

Key facts about Cycas chevalieri

  • Accepted name: Cycas chevalieri Leandri (1931), accepted by The World List of Cycads (version 2026.08.15); POWO could not be consulted directly
  • Former names and synonyms: no synonym of its own; treated as a synonym of Cycas balansae in the Flora of China (1999) and included in Epicycas tonkinensis by de Laubenfels and Adema (1998)
  • Family: Cycadaceae, order Cycadales
  • Common names: none in English; “Cây ngen”, the “Annamese” (Vietnamese) name given by Leandri in 1931
  • Natural range: Vietnam (Nghệ An, Hà Tĩnh, Quảng Bình, Quảng Trị); presence in Laos possible, not confirmed
  • IUCN status: Vulnerable (VU), assessment by J. D. Bösenberg and T. H. Nguyễn published in 2023, VU according to GBIF; criteria shown by The World List of Cycads: A4acd; B1ab(i,ii,iii,iv,v)
  • CITES and other protection: CITES Appendix II; Annex B in the European Union
  • Documented hardiness: no measured value; a British nursery rates it USDA zone 9b without growing data to support it (see Cold hardiness)
  • Light and soil: in the wild, evergreen broadleaved forest, streamsides and rocky limestone slopes, between about 225 and 1,000 m, according to herbarium labels
  • Habit and adult size: trunk unknown to the original description; leaves over 50 cm, leaflets 17 to 27 cm (Leandri 1931); the modern description by Hill and colleagues (2004) could not be consulted
  • In the UK, US and Australia: no record in any botanic garden
  • Toxicity: no analysis specific to the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas chevalieri

The accessible sources allow only a partial portrait. Leandri’s original description (1931), in the Flore générale de l’Indo-Chine, rests on incomplete material: the trunk and male cones are said to be “unknown”. It gives the following characters:

  • Leaves: over 0.5 m long, with a slightly keeled rachis and more than 24 leaflets on each side (exact number unknown).
  • Leaflets: linear-lanceolate, sharply pointed, sometimes slightly sickle-shaped, hairless, constricted just above their insertion, 17 to 27 cm long and about 18 mm wide; midrib 1 mm wide, raised above, sometimes grooved beneath.
  • Megasporophylls (the fertile leaves of female plants): sterile tip very deeply divided right from above the ovules into about ten hairless segments on each side, 3 cm long and 2.5 to 3 mm wide, sometimes forked, around an oval central part 4 cm by 2 cm, covered on one face only, like the top of the stalk, with thick brown down; stalk striate, 3 to 5 cm by 3 to 5 mm, carrying 2 to 4 ovules.
  • Seed: rounded, about 2 cm across, apparently not fully ripe.

A complete, illustrated description was published by Hill, Nguyễn and Lộc in their revision of the Cycas of Vietnam (2004, pages 152–153, figure 4), but it could not be consulted. Detailed measurements found elsewhere (leaves 1.3 to 2.4 m, leaflets 25 to 42 cm, cones, seeds) partly match the description of Cycas balansae in the broad sense of the Flora of China, which included Cycas chevalieri; none could be checked for the species, and they are not used here. Likewise, the claim that the stem is “mostly underground” is supported by no source read: Leandri did not know the trunk.

Hybrids

No natural or garden hybrid is documented. The historical confusion with other species, described below, concerns names and species limits, not hybridisation.

Possible confusion

The risk of confusion lies mainly with the other cycads of northern Indochina with which Cycas chevalieri was long merged. The Flora of China (Chen and Stevenson 1999) included it in Cycas balansae, a species of northern Vietnam and Guangxi; de Laubenfels and Adema (1998) placed it, with Cycas balansae, the variety simplicipinna of Cycas micholitzii (now Cycas simplicipinna) and other names, in a broadly defined Epicycas tonkinensis. Hill and colleagues (2004) separated these species again, but the distinguishing characters they give could not be checked.

In practice, identifying a plant grown as Cycas chevalieri requires reproductive organs and the 2004 revision; its origin (north-central Vietnam, from Nghệ An to Quảng Trị) is a useful clue.

Taxonomy

Cycas chevalieri is accepted by The World List of Cycads; POWO could not be consulted directly. Jacques Leandri described it in 1931 in the account of the Cycadaceae in the Flore générale de l’Indo-Chine (volume 5, part 10, page 1092), citing two collections made for Chevalier: one from “western Tonkin”, without further detail, the other from northern Annam, Nghệ An province (Vinh), “délégation de Nghia-hùng”, at Tram-lui.

The lectotype, kept in the herbarium of the Muséum national d’histoire naturelle in Paris (P), is the collection by F. Fleury for A. Chevalier no. 32612, from Nghia Hung (Tram Lui), Nghĩa Đàn district, Nghệ An; it was designated by Hill, Nguyễn and Lộc in 2004. The Paris herbarium record notes that the sheet was “given by M. Auguste Chevalier in 1943”. The World List of Cycads gives the date of this collection as 20 May 1841, which is obviously wrong, since Chevalier was born in 1873.

The name has had an eventful history. De Laubenfels and Adema, in their 1998 revision that set up the genus Epicycas, placed Cycas chevalieri in the synonymy of Epicycas tonkinensis (type cited: Fleury 32612, P, Nghệ An): in that work tonkinensis is the accepted name for a broadly defined species, not a doubtful name. The Flora of China (1999) sank it into Cycas balansae. The Vietnamese revision by Hill, Nguyễn and Lộc (2004) reinstated it as a species, the position followed by the world checklist. Its placement in a section of the genus was not checked in any source read.

Etymology and history

The epithet honours Auguste Jean Baptiste Chevalier (1873–1956), French botanist, explorer and historian, formerly inspector-general of agriculture and forests in Vietnam, who gathered the type material (Haynes 2022, taken up by The World List of Cycads). The plants on which Leandri based the species were collected for him, at least in part, by F. Fleury.

Leandri knew neither the trunk nor the male cones and thought the seed not fully ripe; the 2004 Vietnamese revision published a modern description. The original description also cites a collection from “western Tonkin”, in the north of the country, which recent sources do not take up: the current range given by the world checklist is limited to north-central Vietnam.

Common names

No English common name is attested, and the specialist nursery Trebrown knows of none. Leandri (1931) gives the “Annamese”, that is Vietnamese, name “Cây ngen” in the protologue; no recent Vietnamese source confirms it.

In the wild

According to The World List of Cycads, Cycas chevalieri is known in Vietnam from the provinces of Nghệ An, Hà Tĩnh, Quảng Bình and Quảng Trị, in the north-centre of the country. A presence in neighbouring Laos is sometimes mentioned but remains unconfirmed: The World List of Cycads and Species+ give Vietnam only, and every occurrence record published on GBIF that states a country comes from Vietnam (GBIF consulted on 25 October 2026).

Herbarium labels published through GBIF describe its habitats: broadleaved evergreen forest on a west-facing slope at about 450 m, and secondary forest, open places and streamsides up to about 1,000 m, in Hương Sơn district (Hà Tĩnh, 1998); alluvial boulder and gravel deposits near a river at Rao An (Hà Tĩnh, 1998); the banks of a stream at 250 to 450 m in Tương Dương district (Nghệ An, 2007); and, in Phong Nha–Kẻ Bàng National Park (Quảng Bình, 2005), primary closed evergreen forest on steep slopes and rocky ridges of eroded crystalline limestone at 560 m, and secondary forest and scrub on limestone slopes at 225 m. Population densities, phenology and regeneration found on other websites probably come from the Red List assessment, which could not be consulted; they are not used here.

Conservation status and regulation

Cycas chevalieri is listed as Vulnerable (VU) by the IUCN. The current assessment, by J. D. Bösenberg and T. H. Nguyễn, was published in Red List version 2023-1 (reference checked on Crossref), and the VU category is confirmed by the IUCN data relayed by GBIF (consulted on 21 October 2026). The World List of Cycads shows the criteria A4acd; B1ab(i,ii,iii,iv,v) and links to the page of that 2023 assessment, while citing as its reference the earlier assessment by H. T. Nguyễn, published in 2010: which of the two these criteria belong to could not be checked. The criteria reflect an observed or projected population reduction linked to habitat decline and collecting, and a limited range in continuing decline. The Red List itself could not be consulted directly.

Like every species in the genus except Cycas beddomei, the species is listed in CITES Appendix II; annotation #4 exempts seeds in particular, whereas live plants require an export permit. Australia, the United Kingdom and the United States apply CITES through their own national legislation; in the European Union it is in Annex B of Regulation (EC) No 338/97, in the version set by Commission Regulation (EU) 2026/1383, applicable since 29 June 2026; Species+ confirms this status. This information does not replace the official texts: check the rules in force before any purchase or exchange, and prefer plants raised from seed in cultivation.

Growing Cycas chevalieri

In short: no growing advice specific to Cycas chevalieri has been published, and the species is not recorded in any botanic garden in the UK, the US or Australia. It does nevertheless circulate among European collectors.

Outdoor and in-ground cultivation

The habitats recorded on herbarium labels (evergreen forest, streamsides, rocky limestone slopes, at low and middle altitudes in a tropical region) point to a plant for frost-free tropical or warm subtropical gardens, in a free-draining soil; how much sun or shade it prefers is not documented. These are deductions, not growing results. In Europe, the Jardí Botànic Marimurtra, at Blanes on the Costa Brava (Spain), declares one accession in BGCI PlantSearch, without saying whether it grows outdoors or under glass.

Container cultivation

On the French forum Fous de palmiers, a grower reported in January 2020 that he had bought young plants the previous summer, with other Asian cycads, without giving any later news. The Jardin zoologique tropical at La Londe-les-Maures, in the south of France, has published nothing on the species. In the absence of specific data, the rules common to tropical Cycas apply: a free-draining substrate that does not hold water around the roots, reduced watering in cool weather, and full protection from frost; in the United Kingdom, that means a heated glasshouse.

In cultivation in the UK, US and Australia

No record. The species does not appear in BGCI PlantSearch for any garden in these three countries (consulted in October 2026), nor in the online catalogues of Montgomery Botanical Center, Fairchild Tropical Botanic Garden, the Royal Botanic Garden Sydney or the Royal Botanic Gardens Victoria. Outside them, BGCI lists Fairy Lake Botanical Garden, in Shenzhen (China), and the Jardí Botànic Marimurtra (Spain). No report from a private grower in the UK, US or Australia could be read.

Propagation

Like all Cycas, Cycas chevalieri is dioecious and is raised from seed: a male and a female plant are needed for fertile seed. No germination data specific to the species have been published, and propagation by offsets, sometimes mentioned, is not documented. Seeds are exempt from CITES under annotation #4; ask for seed from cultivated plants.

Pests and diseases

No pest or disease specific to the species is documented. Like all Cycas, it is exposed to the Asian cycad scale, Aulacaspis yasumatsui, and to stem and root rot in an overly wet substrate.

Cold hardiness

There are no measured cold-tolerance data for Cycas chevalieri. The British nursery Trebrown rates it USDA zone 9b (average annual minimum of −3.9 to −1.1 °C, 25 to 30 °F), but this is a commercial rating, given to many other tropical cycads as well, with no growing observation behind it. No forum message reports a temperature tolerated by the species.

European experience

No result in the open ground has been published in Europe, and no dated frost episode concerns the species. The only plants mentioned on the French forum Fous de palmiers are young plants bought in 2019, with no follow-up published; the garden at Blanes (Spain) that declares it has published no observation. In the absence of data, grow it in a pot, frost-free.

United Kingdom, United States and Australia

No cold reading and no dated growing report are documented. Its range, in north-central Vietnam, is tropical, and no published source gives the minimum temperatures it meets in the wild. Treat it as frost-tender; the zone 9b quoted above is a nursery rating, not a documented result.

Toxicity and precautions

No toxicity analysis specific to Cycas chevalieri has been published. The risk is, however, well documented in the genus: Cycas tissues, and the seeds above all, contain cycasin, which is converted during digestion into methylazoxymethanol, toxic to the liver and nervous system, along with a neurotoxic amino acid, BMAA. The ASPCA lists the sago palm (Cycas revoluta) as poisonous to dogs, cats and horses, with vomiting, sometimes bloody diarrhoea, jaundice and liver damage that can be fatal. Wear gloves to handle the seeds and their pulp, pick up any that fall, and keep plants and seeds out of reach of children and pets. If any part is swallowed, contact a poison centre, a doctor or a vet straight away.

Traditional uses

The published sources describe no traditional use specific to Cycas chevalieri; the Vietnamese name recorded by Leandri shows only that the plant was known locally. Given the toxins of the genus, no part of the plant should be eaten.

Frequently asked questions

Who is Cycas chevalieri named after?

Auguste Chevalier (1873–1956), French botanist and explorer, formerly inspector-general of agriculture and forests in Vietnam, for whom the type material was collected.

Where does it grow?

In north-central Vietnam, in the provinces of Nghệ An, Hà Tĩnh, Quảng Bình and Quảng Trị, in evergreen forest, along streams and on rocky limestone slopes; its presence in Laos is possible but unconfirmed.

Is it the same species as Cycas balansae?

No, according to current taxonomy. The Flora of China (1999) merged them, but the 2004 Vietnamese revision and The World List of Cycads treat them as two distinct species.

What is Epicycas tonkinensis?

The name under which de Laubenfels and Adema (1998) united several cycads of northern Indochina, including Cycas chevalieri and Cycas balansae, in a separate genus, Epicycas. Later revisions did not follow this treatment.

Does it have an above-ground trunk?

This cannot be said for certain from the sources read. Leandri did not know the trunk, and the modern description of 2004 could not be consulted.

Is it endangered?

Yes. The IUCN lists it as Vulnerable (2023), because of habitat decline and collecting. It is protected by CITES (Appendix II) and, in the European Union, by Annex B.

Can it be grown outdoors in the UK?

No, almost certainly not. No cold tolerance has been measured and no outdoor trial is documented; keep it in a pot under frost-free glass.

Is it poisonous?

It must be assumed so. No analysis exists for the species, but all the Cycas studied contain toxins dangerous to people and animals, especially in the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Leandri, J. (1931). Cycadacées. In Lecomte, H. (ed.), Flore générale de l’Indo-Chine 5(10): 1092. Masson, Paris. [Original description of Cycas chevalieri, p. 1092; full text read.]
  • de Laubenfels, D.J. & Adema, F. (1998). A taxonomic revision of the genera Cycas and Epicycas gen. nov. (Cycadaceae). Blumea 43(2): 351–400. [Inclusion of Cycas chevalieri in Epicycas tonkinensis; full text consulted.]
  • Chen, C.J. & Stevenson, D.W. (1999). Cycadaceae. In Wu, Z.Y. & Raven, P.H. (eds), Flora of China, vol. 4: 1–7. Science Press, Beijing; Missouri Botanical Garden Press, St Louis. [Synonymy with Cycas balansae; consulted on eFloras.]
  • Hill, K.D., Nguyễn, T.H. & Lộc, P.K. (2004). The genus Cycas (Cycadaceae) in Vietnam. The Botanical Review 70(2): 134–193. doi:10.1663/0006-8101(2004)070[0134:TGCCIV]2.0.CO;2 [Revision for Vietnam, description on pages 152–153 and lectotypification; text not consulted (paywalled), reference checked via The World List of Cycads.]
  • Nguyễn, H.T. (2010). Cycas chevalieri. The IUCN Red List of Threatened Species 2010: e.T42073A10618818. doi:10.2305/IUCN.UK.2010-3.RLTS.T42073A10618818.en [Earlier assessment; reference checked on Crossref.]
  • Bösenberg, J.D. & Nguyễn, T.H. (2023). Cycas chevalieri. The IUCN Red List of Threatened Species 2023: e.T42073A67339469. doi:10.2305/IUCN.UK.2023-1.RLTS.T42073A67339469.en [Current assessment, VU; reference checked on Crossref, category relayed by GBIF; page not consulted (access blocked).]
  • Haynes, J.L. (2022). Etymological compendium of cycad names. Phytotaxa 550(1): 1–31. doi:10.11646/phytotaxa.550.1.1 [Etymology; taken up by The World List of Cycads.]
  • Calonje, M., Stevenson, D.W. & Osborne, R. (2026). The World List of Cycads, version 2026.08.15. Montgomery Botanical Center, Coral Gables. doi:10.5281/zenodo.21958524 [Reference checklist; consulted directly.]